Superalloys are a broad range of nickel-, iron-, and cobalt-based alloys developed specifically for applications demanding exceptional mechanical and chemical properties at elevated temperatures. The classic use for these alloys is in the hot end of aircraft engines and land based turbines. Almost every metallurgical change made to improve the high temperature properties makes it more difficult to machine these alloys.
As high temperature strength is increased, the alloys become harder and stiffer at the cutting temperature. It results in increased cutting forces and increased wear on the cutting edge during machining.
Because stronger materials generate more heat during chip formation and because the thermal heat conductivity of these alloys is relatively low, very high cutting temperatures are generated, which also contributes to an increased wear of the cutting edge.
To make matters even worse, as the alloys are heat treated to modify the as-cast or solution treated properties, abrasive carbide precipitates or other second phase particles often form. These particles do also cause rapid wear of the cutting edge.
What is needed is a cutting tool insert containing coated cemented carbide, for general wet machining of superalloys, with improved wear resistance. The invention is directed to these, as well as other, important needs.